分析Ext.DataView结合Ext.Panel是怎么样输出数据

Ext.DataView 一种使用定制的模板布局和格式展示数据的机制。 DataView使用一个Ext.XTemplate作为其内部的模板机制， 并被绑定到一个Ext.data.Store， 这样当store中的数据发生变化时视图将自动同步以反应变化。 视图也内建了对许多可能发生的通用事件的处理，包含项目被单击、双击、鼠标滑过、鼠标移出等等， 同时也有一个内建的选择模型（selection model）。为了使用这些特性，必须为DataView提供一个itemSelector配置项， 用来决定与哪个节点配合使用。

   以下是使用Ext.DataView和Ext.Panel输出数据

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01<script type="text/javascript">

02          

03        Ext.onReady(function() {

04  

05            // create the data store

06            varstore =newExt.data.ArrayStore({

07                fields: [

08                   { name:'company'},

09                   { name:'price', type:'float'},

10                   { name:'change', type:'float'},

11                   { name:'pctChange', type:'float'},

12                   { name:'lastChange', type:'date', dateFormat:'n/j h:ia' }

13               ]

14            });

15  

16  

17            // sample static data for the store

18            varmyData = [

19        ['3m Co', 71.72, 0.02, 0.03,'9/1 12:00am'],

20        ['Alcoa Inc', 29.01, 0.42, 1.47,'9/1 12:00am'],

21        ['Altria Group Inc', 83.81, 0.28, 0.34,'9/1 12:00am'],

22        ['American Express Company', 52.55, 0.01, 0.02,'9/1 12:00am'],

23        ['American International Group, Inc.', 64.13, 0.31, 0.49,'9/1 12:00am'],

24        ['AT&T Inc.', 31.61, -0.48, -1.54,'9/1 12:00am'],

25        ['Boeing Co.', 75.43, 0.53, 0.71,'9/1 12:00am'],

26        ['Caterpillar Inc.', 67.27, 0.92, 1.39,'9/1 12:00am'],

27        ['Citigroup, Inc.', 49.37, 0.02, 0.04,'9/1 12:00am'],

28        ['E.I. du Pont de Nemours and Company', 40.48, 0.51, 1.28,'9/1 12:00am'],

29        ['Exxon Mobil Corp', 68.1, -0.43, -0.64,'9/1 12:00am'],

30        ['General Electric Company', 34.14, -0.08, -0.23,'9/1 12:00am'],

31        ['General Motors Corporation', 30.27, 1.09, 3.74,'9/1 12:00am'],

32        ['Hewlett-Packard Co.', 36.53, -0.03, -0.08,'9/1 12:00am'],

33        ['Honeywell Intl Inc', 38.77, 0.05, 0.13,'9/1 12:00am'],

34        ['Intel Corporation', 19.88, 0.31, 1.58,'9/1 12:00am'],

35        ['International Business Machines', 81.41, 0.44, 0.54,'9/1 12:00am'],

36        ['Johnson & Johnson', 64.72, 0.06, 0.09,'9/1 12:00am'],

37        ['JP Morgan & Chase & Co', 45.73, 0.07, 0.15,'9/1 12:00am'],

38        ['McDonald\'s Corporation', 36.76, 0.86, 2.40,'9/1 12:00am'],

39        ['Merck & Co., Inc.', 40.96, 0.41, 1.01,'9/1 12:00am'],

40        ['Microsoft Corporation', 25.84, 0.14, 0.54,'9/1 12:00am'],

41        ['Pfizer Inc', 27.96, 0.4, 1.45,'9/1 12:00am'],

42        ['The Coca-Cola Company', 45.07, 0.26, 0.58,'9/1 12:00am'],

43        ['The Home Depot, Inc.', 34.64, 0.35, 1.02,'9/1 12:00am'],

44        ['The Procter & Gamble Company', 61.91, 0.01, 0.02,'9/1 12:00am'],

45        ['United Technologies Corporation', 63.26, 0.55, 0.88,'9/1 12:00am'],

46        ['Verizon Communications', 35.57, 0.39, 1.11,'9/1 12:00am'],

47        ['Wal-Mart Stores, Inc.', 45.45, 0.73, 1.63,'9/1 12:00am']

48    ];

49  

50      // manually load local data

51      store.loadData(myData);

52  

53      vartpl =newExt.XTemplate('<tpl for=".">',

54                                            '<div class="thumb-wrap">',

55                                               '<table><tr>',

56                                               '<td>{company}</td><td>{price}</td><td>{change}</td><td>{pctChange}</td><td>{lastChange}</td>',

57                                              '</tr></table>',

58                                            '</div>',

59                                        '</tpl>',

60                                       '<div class="x-clear"></div>');

61  

62      varpanel =newExt.Panel({

63                id:'images-view',

64                frame:true,

65                width: 535,

66                autoHeight:true,

67                collapsible:true,

68                layout:'fit',

69                autoHeight:true,

70                title:'Simple DataView',

71  

72                items:newExt.DataView({

73                    store: store,

74                    tpl: tpl,

75                    autoHeight:true,

76                    multiSelect:true,

77                    overClass:'x-view-over',

78                    itemSelector:'div.thumb-wrap',

79                    emptyText:'No images to display'

80                })

81            });

82      panel.render(document.body);

83  

84    });

85</script>

   以下是上面的代码执行之后在IE8中的截图

                                                                                             图(1)
    下面来简单分析下， EXTJS是怎么样呈现这样的界面，其大致执行流程，用以加深对EXTJS的理解，也便于自己日后写扩展。下面的截图是用StarUML画出上面的代码所涉及到有关"类"和组件之间的关系图

                                                                                                      图(2)

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01var panel = new Ext.Panel({

02          //...

03          items:newExt.DataView({

04                    store: store,

05                    tpl: tpl,

06                    autoHeight:true,

07                    multiSelect:true,

08                    overClass:'x-view-over',

09                    itemSelector:'div.thumb-wrap',

10                    emptyText:'No images to display'

11         })

12 });

当实例化Panel时候会先实例化传入的object literal中的items。根据图(2)中Ext.DataView中继承关系和之前一篇文章Extjs- Ext.extend函数的使用知道 Ext.DataView 中传入的object literal中将会传入至Ext.Component的constructor中。

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01Ext.Component = function(config){

02 //...

03  this.getId();

04 //...

05}

06  

07Ext.Component.AUTO_ID = 1000;

08  

09Ext.extend(Ext.Component, Ext.util.Observable, {

10 //...

11 getId :function(){

12        returnthis.id || (this.id ='ext-comp-'+ (++Ext.Component.AUTO_ID));

13 }

14 //...

15});

      执行Ext.Component的constructor方法时会调用this.getId()方法，在上面的代码中没有传入id值。因此得知实例化items的组件的id编号为ext-comp-1001。用firebug查看EXJS生成的HTML可以很清楚的看到

                                                                                                          图(3)

     Ext.Component的constructor方法会调用this.initComponent()方法。当实例化items时候根据图(2)，则会先调用Ext.DataView中的initComponent方法,随后会根据继承关系会向上回溯直至Ext.Component的initComponet，当执行Ext.Component中的initComponent方法之后又会向下回溯至Ext.BoxComponet中的initComponent方法，当执行完Ext.BoxComponent中的initComponent方法又会返回Ext.DataView中继续执行initComponent。中间的细节在此跳过，可以自己查看源码。

     实例化items完后,接下来就会实例化Panel类,同之前过程一模一样,也是会调用Ext.Component的constructor方法。根据图(2)中Ext.Panel的继承关系会依次调用相应的类的initComponent方法。实例化完Panel类时，因为传入了id值为'images-view'这样的话panel的id值将不会自动产生,而是'images-view'。在firebug中查看

                                                                                                           图(4)

 两个组件都已经实例化完成了，接下来会执行panel.render(document.body)。根据图(2)得知会调用Ext.Component的render方法。 

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01Ext.extend(Ext.Component, Ext.util.Observable, {

02     //...

03  render :function(container, position){

04    if(!this.rendered &&this.fireEvent('beforerender',this) !==false){

05             //...

06  

07            this.onRender(this.container, position ||null);

08             

09             //...

10             

11             this.afterRender(this.container);

12            

13             //...

14     }

15     returnthis;  

16   }

17  //...

18});

     当执行到this.onRender(this.container, position || null)时,根据图(2) 则会调用Ext.Panel中的onRender方法。Ext.Panel.supreclass.onRnder.call(this,ct,position) 则会调用Ext.Component中的onRender方法。调用完之后会返回继续执行Ext.Panel中的onRender方法

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01Ext.Panel = Ext.extend(Ext.Container, {

02  

03     //...

04     

05  onRender :function(ct, position){

06  

07   Ext.Panel.superclass.onRender.call(this, ct, position);

08     

09   //...

10  

11 }

12  

13 //...

14  

15});

16  

17Ext.extend(Ext.Component, Ext.util.Observable, {

18  

19  //...

20  

21   onRender :function(ct, position){

22     //..

23   }

24//....

25));

当程序执行到this.afterRender(this.container)时候，查看此时生成EXTJS产生的HTML代码

this.container.dom.innerHTML

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01<divid=images-viewclass=" x-panel"> 

02  <divclass=x-panel-tl> 

03       <divclass=x-panel-tr> 

04         <divclass=x-panel-tc> 

05           <divstyle="MozUserSelect: none; KhtmlUserSelect: none"id=ext-gen4class="x-panel-header x-unselectable"unselectable="on"> 

06             <divid=ext-gen9class="x-tool x-tool-toggle"> </div>

07              <spanclass=x-panel-header-text></span>

08           </div>

09         </div>

10      </div>

11 </div> 

12 <divid=ext-gen5class=x-panel-bwrap> 

13    <divclass=x-panel-ml> 

14      <divclass=x-panel-mr> 

15        <divid=ext-gen8class=x-panel-mc> 

16          <divid=ext-gen6class=x-panel-body></div>

17        </div>

18      </div>

19    </div> 

20    <divid=ext-gen7class="x-panel-bl x-panel-nofooter"> 

21      <divclass=x-panel-br> 

22        <divclass=x-panel-bc></div>

23      </div>

24    </div>

25 </div>

26</div>

this.container.dom.outerHTML

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01<bodyid=ext-gen3class=" ext-ie ext-ie8">

02 <divid=images-viewclass=" x-panel">   

03   <divclass=x-panel-tl>   

04        <divclass=x-panel-tr>   

05          <divclass=x-panel-tc>   

06            <divstyle="MozUserSelect: none; KhtmlUserSelect: none"id=ext-gen4class="x-panel-header x-unselectable"unselectable="on">   

07              <divid=ext-gen9class="x-tool x-tool-toggle"> </div>  

08               <spanclass=x-panel-header-text></span>  

09            </div>  

10          </div>  

11       </div>  

12  </div>   

13  <divid=ext-gen5class=x-panel-bwrap>   

14     <divclass=x-panel-ml>   

15       <divclass=x-panel-mr>   

16         <divid=ext-gen8class=x-panel-mc>   

17           <divid=ext-gen6class=x-panel-body></div>  

18         </div>  

19       </div>  

20     </div>   

21   <divid=ext-gen7class="x-panel-bl x-panel-nofooter">   

22       <divclass=x-panel-br>   

23         <divclass=x-panel-bc></div>  

24       </div>  

25     </div>  

26  </div>  

27 </div> 

28</body>

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<divid=ext-gen6class=x-panel-body></div> 可以看出x-panel-body中什么也没有，因此可以推测出当执行完this.afterRender(this.container)之后。将会将myData中的数据填充到其内部

 接下来分析Ext.Component中的render方法中的this.afterRender(this.container)方法。根据图(2)中的继承关系图可以知道 this.afterRender(this.container)会调用Panel中的afterRender方法。调用Panel中的afterRender方法，沿着继承链向上回溯，Ext.Componet和Ext.BoxComponent中的afterRender方法不是分析的重点，可自行查看源码。当执行到Ext.Container中的afterRender方法时

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01Ext.Container = Ext.extend(Ext.BoxComponent, {

02   

03    //...

04       

05     afterRender:function(){

06        

07        //...

08        if(!this.ownerCt){

09            this.doLayout(false,true);

10         }

11       //...

12     },

13     doLayout :function(shallow, force){

14         

15         //...

16        if(rendered &&this.layout){

17            this.layout.layout();

18        }

19        //...

20    }

21       

22   //... 

23});

当执行到this.layout.layout()的时候,因为传入panel中的object literal 中layout:'fit'则布局为Ext.layout.FitLayout,而Ext.layout.FitLayout继承自Ext.layout.ContainerLayout 如图(2)所示。因此this.layout.Layout将会调用Ext.layout.ContainerLayout中的layout方法

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01Ext.layout.ContainerLayout = Ext.extend(Object, {

02 //...

03  

04   layout :function(){

05     //...

06     this.onLayout(ct, target);       

07     //...

08    },

09   onLayout :function(ct, target){

10        this.renderAll(ct, target);

11    },

12    renderAll :function(ct, target){

13        varitems = ct.items.items, i, c, len = items.length;

14        for(i = 0; i < len; i++) {

15            c = items[i];

16            if(c && (!c.rendered || !this.isValidParent(c, target))){

17                this.renderItem(c, i, target);

18            }

19        }

20    },

21    renderItem :function(c, position, target){

22     if(c){

23         if(!c.rendered) {

24                c.render(target, position);

25                this.configureItem(c);

26          }

27         elseif(!this.isValidParent(c, target)){

28          //...

29          }

30      }

31      

32    }

33//...

34});

调用Ext.layout.ContainerLayout中的layout方法 最终我们将目光锁定在 c.render(target,positon)上,而c参数是由renderAll传入进来的，分析renderAll得知c的执行环境为最先实例化的items 故将调用Ext.DataView中的render方法，通过图(2)得知实质将调用Ext.Component的render方法,当执行Ext.Componet方法的时候，前面已经分析了。当调用this.afterRender,此时this指向Ext.DataView,将调用Ext.DataView的afterRender方法

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01Ext.DataView = Ext.extend(Ext.BoxComponent, {

02  

03 //...

04  

05  afterRender :function(){

06    //...

07   if(this.store){

08            this.bindStore(this.store,true);

09    },

10    bindStore :function(store, initial){

11     //...

12      if(store){

13            this.refresh();

14        }  

15     }

16  },

17   refresh :function() {

18    //...

19    this.tpl.overwrite(el,this.collectData(records, 0));

20   //...

21 }

22//...

23});

this.refresh()是关键之所在，EXTJS将在这个函数将myData填充到模板之中。到处为上已经全部分析完了，要理解这整个过程的前提是你必须对EXTJS有一定的了解，而不只是会简单使用,就像拖拉控件一样。如果这样的话，你会看的云里雾里,建议你还是不要看为好。

链接：http://www.cnblogs.com/yql1986/archive/2011/03/11/1981446.html